The present invention relates to certain 5-substituted dialuric acids having utility in the synthesis of the corresponding hypoglycemic, 5-substituted oxazolidine-2,4-diones. These hypoglycemic oxazolidine-2,4-diones are the subject of a concurrently filed application, entitled "Hypoglycemic 5-Substituted Oxazolidine-2,4-diones", by Schnur.
Dialuric acids have been previously synthesized by the reaction of alloxan hydrates with aromatic amines, phenols, phenol ethers, pyrrole and certain pyrazolones, e.g., ##STR1## [King and Clark-Lewis, J. Chem. Soc., pp. 3080-3085 (1951)] and by the oxidation of barbituric acids, e.g., ##STR2## [Aspelund, Acta. Acad. Aboensis, Math. et. Phys. 10 (14), p. 42 (1937); Chem. Abstracts 31; pp. 6632-6633 (1937)]. It is further understood that dialuric acid is the intermediate in the base catalyzed condensation of substituted tartronic esters with urea, e.g., ##STR3## [King and Clark-Lewis, J. Chem. Soc., pp. 3077-3079 (1951)]. The synthesis of oxazolidine-2,4-diones via dialuric acids has been reviewed [Clark-Lewis, Chem. Rev. 58, pp. 68-71 (1958)].